CVE-2026-55655

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 100% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 6.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.

CVSS v3
6.1
EG Score
6.1MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity61% × 45%
Exploitation0% × 40%
Automatability0% × 15%
EPSS PROB
0.1%
EPSS %ILE
1st
KEV
Not listed

Published

June 23, 2026

Last Modified

September 1, 2026

Advisory Details (2)

Auto-updated Jun 23, 2026
Patch available. Sources: redhat.
redhat

2462250 – (CVE-2026-55655) CVE-2026-55655 openssh: Local MITM of X11 forwarding via abstract UNIX socket pre-binding in Red Hat Enterprise Linux OpenSSH client versions

https://bugzilla.redhat.com/show_bug.cgi?id=2462250
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-55655

Vendor Advisories for CVE-2026-55655(8)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhui5/rhua-tp-rhel9:17872412602026-08-24redhat
redhatrhui5/rhua-rhel9:17865335292026-08-12redhat
redhatopenssh-0:8.0p1-30.el8_102026-07-30redhat
redhatopenssh-0:9.9p1-25.el10_22026-07-30redhat
redhatopenssh-0:9.9p1-9.el9_82026-07-29redhat
redhatopenssh-main-10.3p1-6.hum12026-07-08redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-1 ... 1:9.9p2-2 (86 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-1 ... 1:9.9p2-2 (75 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-7 ... 1:10.4p1-4 (29 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
openssh1:10.0p1-7 ... 1:10.4p1-4 (25 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 217 total refreshes for this CVE.

  1. 2026-10-04 23:22 UTCEPSS rescore
  2. 2026-10-03 14:26 UTCEPSS rescore
  3. 2026-10-02 17:56 UTCEPSS rescore
  4. 2026-10-01 19:50 UTCEPSS rescore
  5. 2026-09-30 15:03 UTCEPSS rescore
  6. 2026-09-29 15:22 UTCEPSS rescore
  7. 2026-09-28 13:51 UTCEPSS rescore
  8. 2026-09-27 13:48 UTCEPSS rescore
  9. 2026-09-26 15:59 UTCEPSS rescore
  10. 2026-09-24 14:04 UTCEPSS rescore
  11. 2026-09-23 17:54 UTCEPSS rescore
  12. 2026-09-18 11:12 UTCEG score recompute
  13. 2026-09-18 11:12 UTCVendor advisory
  14. 2026-09-18 11:12 UTCGHSA enrichment
  15. 2026-09-17 19:31 UTCEPSS rescore
  16. 2026-09-16 14:08 UTCEPSS rescore
  17. 2026-09-16 05:15 UTCEPSS rescore
  18. 2026-09-13 16:47 UTCEPSS rescore
  19. 2026-09-13 12:28 UTCEG score recompute
  20. 2026-09-13 12:28 UTCVendor advisory
  21. 2026-09-13 12:28 UTCGHSA enrichment
  22. 2026-09-11 14:53 UTCEPSS rescore
  23. 2026-09-10 09:35 UTCEPSS rescore
  24. 2026-09-08 22:01 UTCEPSS rescore
  25. 2026-09-06 13:47 UTCEPSS rescore
Show 75 more
  1. 2026-09-04 05:06 UTCEPSS rescore
  2. 2026-09-02 14:12 UTCEPSS rescore
  3. 2026-09-01 13:54 UTCEPSS rescore
  4. 2026-09-01 09:34 UTCVendor advisory
  5. 2026-09-01 09:34 UTCGHSA enrichment
  6. 2026-09-01 08:56 UTCVendor advisory
  7. 2026-09-01 08:56 UTCGHSA enrichment
  8. 2026-08-30 20:28 UTCEG score recompute
  9. 2026-08-30 20:28 UTCVendor advisory
  10. 2026-08-30 20:28 UTCGHSA enrichment
  11. 2026-08-26 14:46 UTCEPSS rescore
  12. 2026-08-25 13:49 UTCEPSS rescore
  13. 2026-08-25 10:22 UTCVendor advisory
  14. 2026-08-25 10:22 UTCGHSA enrichment
  15. 2026-08-25 09:57 UTCEG score recompute
  16. 2026-08-25 09:57 UTCVendor advisory
  17. 2026-08-25 09:57 UTCGHSA enrichment
  18. 2026-08-24 13:55 UTCVendor advisory
  19. 2026-08-24 13:55 UTCGHSA enrichment
  20. 2026-08-23 14:13 UTCEG score recompute
  21. 2026-08-23 14:13 UTCVendor advisory
  22. 2026-08-23 14:13 UTCGHSA enrichment
  23. 2026-08-23 00:19 UTCEPSS rescore
  24. 2026-08-22 14:52 UTCVendor advisory
  25. 2026-08-22 14:52 UTCGHSA enrichment
  26. 2026-08-21 12:20 UTCVendor advisory
  27. 2026-08-21 12:20 UTCGHSA enrichment
  28. 2026-08-21 12:15 UTCVendor advisory
  29. 2026-08-21 12:15 UTCGHSA enrichment
  30. 2026-08-20 16:15 UTCEG score recompute
  31. 2026-08-20 16:15 UTCVendor advisory
  32. 2026-08-20 16:15 UTCGHSA enrichment
  33. 2026-08-19 17:04 UTCEPSS rescore
  34. 2026-08-19 14:17 UTCVendor advisory
  35. 2026-08-19 14:16 UTCGHSA enrichment
  36. 2026-08-18 14:54 UTCEG score recompute
  37. 2026-08-18 14:54 UTCVendor advisory
  38. 2026-08-18 14:54 UTCGHSA enrichment
  39. 2026-08-18 13:48 UTCEPSS rescore
  40. 2026-08-17 13:47 UTCEPSS rescore
  41. 2026-08-17 13:43 UTCVendor advisory
  42. 2026-08-17 13:43 UTCGHSA enrichment
  43. 2026-08-16 14:22 UTCEG score recompute
  44. 2026-08-16 14:22 UTCVendor advisory
  45. 2026-08-16 14:22 UTCGHSA enrichment
  46. 2026-08-16 02:14 UTCEPSS rescore
  47. 2026-08-15 15:00 UTCEG score recompute
  48. 2026-08-15 15:00 UTCVendor advisory
  49. 2026-08-15 15:00 UTCGHSA enrichment
  50. 2026-08-15 01:30 UTCEPSS rescore
  51. 2026-08-14 15:38 UTCVendor advisory
  52. 2026-08-14 15:38 UTCGHSA enrichment
  53. 2026-08-13 16:16 UTCVendor advisory
  54. 2026-08-13 16:16 UTCGHSA enrichment
  55. 2026-08-12 16:36 UTCVendor advisory
  56. 2026-08-12 16:36 UTCGHSA enrichment
  57. 2026-08-12 16:04 UTCVendor advisory
  58. 2026-08-12 16:04 UTCGHSA enrichment
  59. 2026-08-12 13:08 UTCVendor advisory
  60. 2026-08-12 13:08 UTCGHSA enrichment
  61. 2026-08-11 13:44 UTCEG score recompute
  62. 2026-08-11 13:44 UTCVendor advisory
  63. 2026-08-11 13:44 UTCGHSA enrichment
  64. 2026-08-11 00:00 UTCEPSS rescore
  65. 2026-08-10 14:22 UTCVendor advisory
  66. 2026-08-10 14:22 UTCGHSA enrichment
  67. 2026-08-09 15:00 UTCEG score recompute
  68. 2026-08-09 15:00 UTCVendor advisory
  69. 2026-08-09 15:00 UTCGHSA enrichment
  70. 2026-08-08 16:37 UTCEPSS rescore
  71. 2026-08-08 15:39 UTCEG score recompute
  72. 2026-08-08 15:39 UTCVendor advisory
  73. 2026-08-08 15:39 UTCGHSA enrichment
  74. 2026-08-07 16:16 UTCVendor advisory
  75. 2026-08-07 16:16 UTCGHSA enrichment

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55655?
CVE-2026-55655 is a medium vulnerability published on June 23, 2026. A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can…
When was CVE-2026-55655 disclosed?
CVE-2026-55655 was first published on June 23, 2026, with the most recent update on September 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55655 actively exploited?
CVE-2026-55655 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (1st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55655?
CVE-2026-55655 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-55655?
A fix for CVE-2026-55655 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55655 are linked in the Vendor Advisories panel on this page.

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